Photodissociation effects on the electron density and on FTIR measurements in a BTMSM/Ar discharge

For precise measurements of the absolute electron density in a bis-trimethylsilymethane (BTMSM) and argon plasma, the authors adapted a wave cutoff method and used the plasma frequency. The films were deposited on a p-type Si(1 0 0) substrate by means of UV-assisted inductively coupled plasma-enhanced chemical vapour deposition. Fourier transform infrared spectroscopy was used to investigate the bonding configuration of the SiCH films. With UV illumination, the electron density was found to increase in the low power region and decrease in the high power region. The peak intensity of Si-CH3 decreases with UV illumination under all conditions. Moreover, when the UV source illuminates the plasma, the peak intensity of CH2 increases whereas the peak intensity of CH3 decreases.